The present invention relates to a seat belt device for protecting a vehicle occupant, particularly to a seat belt device in which a seat belt retractor is incorporated in a seat back. More particularly, the present invention relates to the seat belt device in which an acceleration sensor always stands vertically at any reclining angle of the seat back.
As well known, a seat belt device restrains an occupant to a vehicle seat with a webbing unwound from a real of a retractor in order to protect the occupant when the vehicle comes into collision. In this seat belt device, a locking mechanism is actuated to stop the reel to rotate when deceleration applied to the vehicle in the horizontal direction exceeds a predetermined value. An acceleration sensor for detecting the deceleration has a sensor weight capable of tilting which tilts to a rolling-over side due to the deceleration in the horizontal direction.
A seat belt retractor may be incorporated in a seat back, whereby, a webbing fits well the occupant, at any angle of inclination of the seat back.
The seat belt retractor incorporated in the seat back requires to be provided with a mechanism for controlling the acceleration sensor to stand vertically at any angle of inclination of the seat back. A mechanism for controlling the acceleration sensor disclosed in the U.S. Pat. No. 5,716,102 has a pulley attached to a portion where the seat back and the seat cushion are connected to each other, and a cable one of ends of which is wound onto a pulley integrated with the acceleration sensor, so that the cable rotates the pulley integrated with the acceleration sensor according to the pivotal movement of the seat back in the rearward incline direction to stand the sensor vertically.
The cable is a release style cable having a sheath-like outer tube and is able to deliver not only a tension but also a pressure.
It is hardly possible to install the seat belt device of the U.S. Pat. No. 5,716,102 in a vehicle, since even a minute error of a length of the cable or the outer tube brings a large drift of the acceleration sensor from the vertical direction.